The telescope will be at L2.
https://en.wikipedia.org/wiki/Nancy_Grace_Roman_Space_Telescope
I really like the "KNOBS are greater than MENUS" sign. For years we have been saying that menus are for restaurants. FB Steve.
Steve's resotation man-cave is very interesting, as are the rigs he has on the shelf or on the bench. Lots of good work is obviously being done there.
I also have one of those KP4USA QSL cards. Steve and I got into ham radio at around the same time, so it is possible that he was on the other end of that QSO. I will check.
Check out Steve's QRZ page: https://www.qrz.com/db/KW4H
We've been proponents of this idea for a long time: Essentially it is that sometimes you have to at least temporarily put a hard technical problem on hold. Sometimes you need to just STOP working on the problem, put the rig on the shelf, and go out and take a walk. Or, perhaps, a hike.
In the travel section of the New York Times today, I found this phrase from Latin: "solvitur ambulando." It was in an atricle by one of my favorite authors, Paul Theroux. One of his his novels, "The London Embassy" was eerily true to life, and had me thinking that the house he described was, in fact, the house in London that I was living in. Paul has been at it for so long that, frankly, I thought he was gone. I was delighted to learn that he is not, and that he is still writing books.
Theroux wrote, "Is something fuddled in your mind? Searching for an idea? Then lace your boots, leave the house, and set off alone: Chances are you will find the answer along the way. This remedy (attributed variously to Diogenes the Cynic and St. Augustine) is one that all true piligrims know, and in many respects serious hikers are the modern embodiment of medieval pilgrims."
Indeed, if the solution is fuddled in your mind and you are searching for an idea, take a break, do something different. Take a walk: "solvitur ambulando."
Here is a really nice New York Times story about NASA efforts to keep the Voyager spacecraft alive. They are approaching 50 years old. They are very far away. They are running low on the plutonium that keeps them warm and powered. The fuel for the thrusters is starting to clog the pipes. But NASA recently carried out a "Big Bang" effort to extend the life of these two spaccraft.
One of the 25 year-old engineers admitted that he treats the Voyagers like he treats his aging parents -- problems do crop up. But then he was reminded that his parents had been born AFTER the launch of the Voyagers.
The animation above shows where the two spacecraft are, and where they have been.
I really liked this one, and the follow-on videos show a lot of promise. The maker starts with the four equations that we see on T shirts. He admits that at the time he first saw them, he did not understand. But in this video, he digs in, and finally gets it. The connection between Maxwell's equations and C (the speed of light) are especially well presented.
There is a document that goes quite a bit further, and explores the connections between Maxwell's equations and quantum mechanics. It is by that wonderful physicist Freeman Dyson. It is entitled "Why is Maxwell's theory so hard to understand?" Check it out:
https://davidtong.org/pdfs/teaching/electromagnetism/dyson.pdf
Video version: https://www.youtube.com/watch?v=_hbLmsFxzx4
Audio version: http://soldersmoke.com/soldersmoke266.mp3
Travelogue: Dean to Boston, Bill to Glenmore in Maryland.
Discussion of AI, data centers, and ham radio.
Dean's Bench:
-- Troubleshooting
-- Why we emphasize building in stages
-- Helge LA6NCA's Rig
-- Troubleshooting when the data fools you: The ZIA rig.
SHAMELESS COMMERCE DIVISION:
-- Mostly DIY RF.
-- Please continue to comment on blog posts.
-- Please think about becoming a Patreon sponsor/
Bill's Bench:
-- Working Australia on 20 and 17 SSB.
-- Putting 80 meter antenna back up. But high (August) noise level on 75. SOLVED!
-- Nuvistor adventures with 1964 Parks Electronics Converter. 6CW4s.
-- Thinking of audio derived S-meters.
Mailbag:
Grayson KJ7UM -- admiration for Helge LA6NCA. 6L6 Rig.
Hidehiko JA9MAT's super regen, And FT-101 VFO Box.
Chuck WB9KZY on older UK covert listening devices.
Paul VK3HN: Australian CBLA rig.
Andri in Bandung, Indonesia -- Built a SolderSmoke DC receiver. 137 built so far!
Mike WN2A liked 3885 kHz post (not everyone did -- AI Slop?)
Walter KA4KXX liked piece on G0UPL breaking the I and Q code of Si5351.
Bob KD4EBM and Peter VK3TPM on AI.
Ryan KJ7KVD will build MMM when family duties permit.
Chris KD4PBJ noted SolderSmoke on a ham radio sign sheet. FB.
Eric 4Z1UG -- Interviewed Will N5OLA (Heathkit Guy) https://www.qsotoday.com/podcasts/n5ola
K6AUS seeking understanding on mixers. FB!
K6AUS: Did Drake make any 2Bs with serial numbers 3000-4000? https://nomadiq.net/blog/post/how-many-drake-2bs-were-ever-made
I am still looking for a Drake 2B for K6AUS.
NT0Z -- Kirk. A big fan. Thanks.
I have seen Schenectady and even Springfeld (see below!) but Lahti was new to me. I spotted it yesterday on the dial of the receiver that the fellow from the UK was fixing. Lahti? What was that?
Turns out, this is a European Longwave thing.
Gemini explains:
When you see Lahti printed on the dial of an older radio, it is typically marking a Longwave (LW) broadcast frequency rather than a shortwave frequency.
The presence of Lahti on the dial relates to several historical factors:
The Lahti High-Power Station: Located in Lahti, Finland, the national broadcaster Yle operated a massive, high-power longwave transmission station on "Radio Hill" (Radiomäki) starting in the late 1920s.
Dial Navigation: On older European and world-band radio dials, manufacturers frequently printed the names of major high-power European broadcasting cities (such as Lahti, Rome, Berlin, Moscow, or Droitwich) directly onto the glass or metal scale. Because consumers tuned radios by city or wavelength rather than just abstract kilohertz numbers, these city names served as benchmark reference points for specific frequencies (such as Lahti's long-standing assignment on the longwave band, which eventually settled on 252 kHz).
The Era of "All-Wave" and Multi-Band Radios: Older vintage receivers—particularly those manufactured in Europe or targeted at international markets—often featured multiple bands spanning Longwave, Medium Wave (AM), and Shortwave. Even if a radio is broadly referred to as a "shortwave" or multi-band radio, its dial layout almost always incorporated the Longwave band where powerhouse European utility and broadcasting stations like Lahti lived prior to the widespread decommissioning of European LW transmitters in the late 20th century.
Crikey! Blimey! The parts are wonky! Then he fixes it and they are all lovely! These are some great descriptive words that you just won't hear in a U.S. workshop. Pity.
I liked the receiver. I had never seen one of these.
The Ultrasonic cleaner was nice. As was the oven.
His repair of the switches was very cool. I like his technique for repairing the many leads that got broken.
When he started unplugging the plugs on the boards, I got nervous. Pull out the cell phone and take some pictures first!
Opening up those old pots was really going the extra mile. I would have just squirted some deoxit in them.
He ended up changing almost all the caps on the AF amplifier board. The Capacitor Police would indeed been annoyed.
Great job. It was fun watching him work. But what would you guys have done differently? Please comment below.
Thanks to Rogier PA1ZZ for sending me this.
https://www.qsotoday.com/podcasts/n5ola
This interview was a lot of fun. I too was smitten at an early age by the HW-101. I still have one on my operating table. We are all lucky that Will is working in an innovative way on these old rigs. Who can forget his shocking water and soap (followed by South Texas sunshine) approach to cleaning these often cruddy old rigs? Thanks Will and thanks Eric for doing this interview.
Please post your comments below.
 |
| Updated image to show quenching |
The operation of the superregenerative receiver is complex and difficult to analyze in detail. As noted by Thomas H. Lee, it "has never been understood by more than a handful of people at a given time."[22]
https://en.wikipedia.org/wiki/Superregenerative_receiver
-------------------------------------------
This is from Gemini AI:
WHAT IS THE BENEFIT OF SUPER-REGENERATION?
When operating on the 2-meter band, switching from a standard regenerative detector to a super-regenerative detector yields a massive jump in single-stage receiver gain—typically an additional 40 to 60 dB -- a voltage amplification factor of 100 to 1,000 times greater.
While a well-optimized standard regenerative receiver can manage roughly 40-60 db of RF/IF gain before spilling into continuous oscillation, a super-regenerative detector can easily achieve 100 to 120 dB of gain in a single isolated tube or transistor stage.
Here is why that delta is so profound, especially at VHF:
Regeneration (The Knife Edge): A standard regenerative receiver relies on positive feedback adjusted to sit just below the point of self-oscillation. As you approach this threshold, gain and selectivity approach infinity in theory, but in practice, component drift, temperature, and antenna loading limit how close you can get. At 144 MHz staying on this knife-edge is notoriously difficult.
Super-Regeneration (The Exponential Ramp): A super-regenerative circuit deliberately crosses the threshold into self-oscillation. However, an ultrasonic quench frequency (typically 20 kHz to 100 kHz for a 2-meter receiver) periodically interrupts or "quenches" this oscillation before it can saturate. Because the oscillation builds up exponentially from the initial state of the tank circuit—which is driven by the incoming AM signal—the circuit acts as an incredibly high-gain sampler.
Sensitivity: Because of that extra 40 to 60 dB of gain, a super-regen can easily pull a microvolt-level AM signal out of the noise floor, whereas a standard regen at VHF would require an external RF amplifier stage to match that sensitivity.
Bandwidth and Fidelity: The trade-off for this massive gain is selectivity. Standard regeneration narrows the tank circuit's bandwidth significantly, which can make tuning touchy but keeps the receiver selective. Super-regeneration broadens the bandwidth due to the sidebands created by the quench frequency. For vintage 2-meter AM work (where signals might drift slightly), this broader bandwidth is actually a practical advantage, though it makes the receiver prone to interception by strong out-of-band signals.
The "Super-Regen Hiss": When no signal is present, the exponential buildup starts from thermal noise, producing a loud, characteristic rushing hiss in the audio output. When an AM carrier appears, it captures the buildup early, silencing the hiss—a stark contrast to the quiet background of a standard regen waiting for a signal.
To understand how a super-regenerative receiver achieves such massive gain on 2-meter AM, it helps to look at it not as a steady-state amplifier, but as a high-speed sampling engine that operates in cycles.
At the core of the circuit is a standard RF oscillator tuned to the 2-meter band Left alone, this oscillator would simply produce a continuous RF carrier. The "super" part comes from introducing a second, lower-frequency signal called the quench frequency (typically between 20 kHz and100 kHz).
Here is the step-by-step breakdown of exactly what happens during a single quench cycle:
The quench oscillator constantly varies the bias of the 2-meter detector stage, swinging it back and forth between two states: sub-critical (where it cannot oscillate) and super-critical (where it desperately wants to oscillate).
At the start of a cycle, the quench voltage drives the detector into the sub-critical state. Any previous oscillations are completely wiped out. The circuit is wiped clean and made ready to sample the antenna.
As the quench voltage swings, the detector enters the super-critical state. RF energy begins to build up in the 144 MHz tank circuit. Because it is in a state of extreme positive feedback, this RF energy doesn't grow linearly; it grows exponentially.
However, an oscillator cannot start growing from absolute zero. It needs a "seed" to kick off the oscillation. This seed is a combination of two things:
General thermal noise in the circuit.
The incoming 2-meter AM radio signal from the antenna.
If a weak AM signal is present on the antenna, its voltage combines with the background noise. Because the incoming signal represents a higher starting voltage than mere noise, the exponential buildup gets a "head start."
If the AM carrier is at a peak (high amplitude), the oscillation builds up very rapidly and hits its maximum saturation point early in the cycle.
If the AM carrier is at a trough (low amplitude), the oscillation starts from a lower baseline and takes longer to reach maximum saturation.
Because the RF oscillations reach saturation faster or slower depending on the strength of the incoming signal, the total energy or average current consumed by the detector tube or transistor during that cycle changes.
Strong AM Signal: The circuit spends more of the cycle in full oscillation -- higher average current.
Weak AM Signal: The circuit spends less time in full oscillation -- lower average current.
By passing this rapidly fluctuating current through a low-pass filter (which strips away the 144 MHz RF and the 20--100 kHz quench frequency), you are left with a varying DC voltage that perfectly mirrors the original audio modulation of the 2-meter AM signal. This is routed directly to an audio amplifier and your speaker.
This sampling process happens tens of thousands of times per second—well above the range of human hearing.
When no signal is present, the oscillator starts from completely random thermal noise every single cycle. Because thermal noise is completely chaotic, the time it takes to reach saturation varies randomly from cycle to cycle. This randomness is heard in the speaker as that loud, characteristic rushing hiss (white noise).
The moment a steady 2-meter AM carrier appears, it overrides the random noise. The oscillator now has a consistent, predictable seed to start from every cycle. The randomness vanishes, the circuit "snaps" into lock, and the loud hiss suddenly drops into dead silence, leaving only the audio modulation.
IF IT IS SO MUCH BETTER, WHEY DON'T WE USE SUPER-REGENERATION ON HF?
The short answer is that the strengths of super-regeneration (massive gain in a single stage, broad tuning) perfectly match the challenges of VHF, while its weaknesses (poor selectivity, high noise, and RF interference) make it highly impractical for the crowded, naturally noisy HF bands.
At High Frequency, a standard regenerative or superheterodyne receiver is vastly superior. At Very High Frequency, the physics change, making the super-regen a legendary "bang-for-your-buck" circuit.
Here is a breakdown of why this divide exists:
A super-regenerative detector works by constantly quenching and restarting an oscillator. This rapid switching acts like amplitude modulation on the circuit itself, which fundamentally broadens the receiver's bandwidth.
At VHF (e.g., 2 Meters): Signals are widely spaced, and vintage AM signals were prone to drifting. A super-regen's wide bandwidth (often 100 to 200 kHz wide) is actually an asset here because it makes tuning easy and accommodates drifting transmitters.
At HF (e.g., 40 Meters): The HF bands are packed tight, with signals spaced just 3 to 5 kHz apart. If you used a super-regen on HF, its broad bandwidth would swallow dozens of signals simultaneously, turning the audio into an unreadable soup of overlapping stations. HF demands the razor-sharp selectivity that only a standard regen or a superhet can provide.
The primary reason you need a high-gain receiver changes depending on where you are in the spectrum.
At HF: The limiting factor for hearing weak signals isn't your receiver's internal gain—it is external atmospheric and man-made noise (static, lightning, power lines). Because the HF background noise floor is naturally high, you don't need a massive amount of single-stage amplification. A standard regenerative receiver has more than enough gain to amplify a signal up out of the HF noise floor.
At VHF: Cosmic and atmospheric noise drop off sharply at VHF. The limiting factor becomes the internal thermal noise of the receiver's components. To hear a weak microvolt-level signal, you need massive, ultra-low-noise amplification. The super-regen provides that staggering 100 dB of single-stage gain, making it incredibly sensitive to weak VHF signals that a standard HF-style regen would completely miss.
For a super-regenerative detector to work properly, the quench frequency must be significantly lower than the operating RF frequency, but significantly higher than the highest audio frequency 3 kHz for voice).
Ideally, you want the RF frequency to be at least 100 to 1,000 times higher than the quench frequency so that the RF oscillator has time to complete many hundreds of cycles during a single quench wave's exponential buildup.
At VHF: A quench frequency of 50 kHz fits perfectly. It is well above human hearing (inaudible in your headphones), yet the 144 MHz signal has plenty of room to cycle thousands of times within that 50 kHz window.
At lower HF (3.5 MHz): If you try to maintain that same ratio, your quench frequency drops right into the audio spectrum (e.g., 5 to10 kHz). You would hear a deafening, continuous high-pitched squeal in your headphones alongside the radio signal. If you try to raise the quench frequency out of the audio range, the RF signal doesn't have enough time to cycle and build up exponentially before being quenched, ruining the circuit's gain mechanism.
Because a super-regen is literally a high-power oscillator being driven into heavy saturation tens of thousands of times per second, it acts as a small spark-gap transmitter. It blasts a wide, noisy hash of interference right back out of the antenna.
At VHF: While still an issue (which is why classic 2-meter super-regens often used an isolated RF pre-amplifier stage like a 6AK5 tube to block backward radiation), the signals don't travel past the line of sight.
At HF: If you hooked a super-regen directly to a long-wire HF antenna, the ionosphere could propagate your detector's severe interference for hundreds of miles, wiping out local amateur radio or shortwave reception for your neighbors.
